Functions of corazonin and histamine in light entrainment of the circadian pacemaker in the Madeira cockroach,Rhyparobia maderae

Abstract

The circadian pacemaker of the Madeira cockroach, Rhyparobia (Leucophaea) maderae, is located in the accessory medulla (AME). Ipsi- and contralateral histaminergic compound eyes are required for photic entrainment. Light pulses delay locomotor activity rhythm during the early night and advance it during the late night. Thus, different neuronal pathways might relay either light-dependent delays or advances to the clock. Injections of neuroactive substances combined with running-wheel assays suggested that GABA, pigment-dispersing factor, myoinhibitory peptides (MIPs), and orcokinins (ORCs) were part of both entrainment pathways, whereas allatotropin (AT) only delayed locomotor rhythms at the early night. To characterize photic entrainment further, histamine and corazonin were injected. Histamine injections resulted in light-like phase delays and advances, indicating that the neurotransmitter of the compound eyes participates in both entrainment pathways. Because injections of corazonin only advanced during the late subjective night, it was hypothesized that corazonin is only part of the advance pathway. Multiple-label immunocytochemistry in combination with neurobiotin backfills demonstrated that a single cell expressed corazonin in the optic lobes that belonged to the group of medial AME interneurons. It colocalized GABA and MIP but not AT or ORC immunoreactivity. Corazonin-immunoreactive (-ir) terminals overlapped with projections of putatively light-sensitive interneurons from the ipsi- and contralateral compound eye. Thus, we hypothesize that the corazonin-ir medial neuron integrates ipsi- and contralateral light information as part of the phase-advancing light entrainment pathway to the circadian clock. J. Comp. Neurol. 525:1250-1272, 2017. © 2016 Wiley Periodicals, Inc.

Insights Into Sexual Maturation and Reproduction in the Norway Lobster (Nephrops norvegicus) via in silico Prediction and Characterization of Neuropeptides and G Protein-coupled Receptors

“…This absence could be explained by: (a) GnRH/GnRH-like is stage-specific, and transcriptomic analysis has not been conducted on the appropriate stage, (b) GnRH/GnRH-like is not present in all crustacean species, and those GnRH identified in crustaceans have functions unrelated to reproduction, or (c) AKH and ACP represents a class of GnRH-like that have arisen by gene duplication in the arthropod lineage, as elucidated recently by Zandawala et al ( 69 ). One of the closest related neuropeptides to GnRH, in terms of primary amino acid sequence, is Crz, a neuropeptide which was originally assigned as a cardioactive peptide ( 70 ), and then has been proven to hold a wide range of functions including within the context of stress ( 71 – 73 ), pigmentation ( 74 ), ecdysis ( 75 ), and circadian rhythm ( 76 ). As reviewed recently, the role of Crz in crustaceans reproduction is still uncertain ( 21 ).…”

Circadian pacemaker neurons of the Madeira cockroach are inhibited and activated by GABAA and GABAB receptors

“…The GABAergic distal tract and the GABAergic medial layer fibre tract connect the AME to the medulla. Most prominently they connect to the medial layer fibre system of the medulla that serves as an input and output region to the clock (Arendt, Baz, & Stengl, ; Giese et al., ; Reischig & Stengl, ). In the medial layer fibre system different neuropeptidergic neurons arborise such as the PDF‐neurons that control light inputs and phase shift locomotor activity rhythms in the fruit fly and in the cockroach (reviews: Stengl et al., ; Stengl & Arendt, ; Helfrich‐Förster, ).…”

Distribution and daily oscillation of GABA in the circadian system of the cockroach Rhyparobia maderae

“…For triple immunolabeling using antisera raised in the same species, fluorescently labeled and unlabeled monovalent Fab fragments were used as secondary antibodies to prevent the second secondary antibody from binding to the first primary antibody (Arendt et al, 2017;Giese et al, 2018a). For triple immunolabeling of GABA, histamine, and PDF, dissected brains were submerged in freshly prepared 4% N-(3dimethylaminopropyl)-Nt'ethylcarbodiimide (EDAC; E-7750; Sigma-Aldrich) in PBS for 3 h on ice.…”